Motor control switching system and device therefor



y 1943- D. J. BLOOMBERG EI'AL 2,445,320

. MOTOR CONTROL SWITCHING SYSTEM AND DEVICE THEREFOR 1 Filed larch 31, 1945 3 Sheets-Sheet 1 IN VEN TORS M 3 9 l v K/aZ all am fi777'02/VE) July 27, 1948. o. J BLOOMBERG ETAL 2,445,320

MOTOR CONTROL SWITCHING SYSTEM AND DEVICE THEREFOR Filed March 31, 1945 3 Sheets-Sheet '2 N62 QokbwQbQQ July 27, 1948 VD. J. BLOOMBERG EI'AL 2,445,820

- MOTOR CONTROL SWITCHING SYSTEM AND DEVICE THEREFOR I Filed March 31, 1945 3 Sheets-S ee 3 INVENTOR$ cam-(Jigsaw; w 0.10m MM HTTOQNEV Patented July 27, 1948 MOTOR CONTROL SWITCHING SYSTEM AND DEVICE THEREFOR Daniel J. Bloomberg, Sherman om, and Waldon 0. Watson, North Hollywood, Calif., assignors to Radio Corporation oi America, a corporation of Delaware Application March 31, 1945, Serial No. 585,914

9 Claims. 1

This invention relates to electrical switching systems for plural phase electrical motors, and particularly to an electrical switching system for use with self-synchronizing motors in motion picture sound recording studios wherein different film advancing mechanisms such as sound reproducers, sound recorders, cameras, etc., are interconnected to advance a plurality of films in synchronism.

The use of self-synchronizing motor systems wherein three-phase rotor and stator wound induction motors are employed. are well known, such systems utilizing a distributor-generator and a synchronous driving motor therefor. In these systems, the stators of the synchronous motor, the distributor, and the load motors are all connected to a three-phase alternating current power source, while the rotors of the distributor and load motors are interconnected. As the synchronous driving motor rotates the rotor of the distributor, current flows between the rotors, which causes them to accelerate and rotate in step with one another. Examples of such commercial motor systems are shown in Lootens Patent No. 2,301,910, of November 10, 1942, and Miller Patent No. 2,354,329, of July, 25, 1944.

The above-mentioned patents disclose methods of and means for starting a predetermined number of load motors after they have been selected. The present invention is directed to a system for selecting and connecting certain load motors with a selected distributor, which after connection, may be started in the manner shown in these patents.

In motion picture practice, a number of distributors are required because it is necessary to use a distributor for each interconnected system of load motors and several systems may be operated simultaneously. For instance, if it is desired to re-record previously recorded sound tracks using soundheads or film phonographs and a recorder as one system, and at the same time operate a camera and a recorder for making an original sound record as another system, one distributor will be connected to the sound-heads and recorder, and another distributor will be connected to the camera and its recorder. Many times four or five such systems may be operating simultaneously, since in a motion picture studio, many soundheads are employed for rerecording, and it is necessary to employ several recorders to 2 soundheads, recorders, and cameras, to a certain distributor in the event that a articular operation requires that combination,

This general method of ope t fl is t w. but it has been accomplished in the past by the use of large terminal panels together with connecting cords similarly to a telephone switchboard. Such installations required considerable space and the interlacing of cables, which are not particularly convenient to operate. The present invention eliminates all such cables and simplifies the interconnecting of any load motor to a chosen distributor by simply turning a switch to the distributor number and closing th switch. This cannot, of course, be accomplished with the usual type of sliding contact switch, as will be explained hereinafter.

The principal object of the invention, therefore, is to facilitate the selection and interconnecting of the motors of a number of film advancing mechanisms with any one of a plurality of distributors.

Another object of the invention is to provide an improved method of and means for selecting and interconnecting a plurality of motors, distributors, or similar electrical devices.

A further object of the invention is to provide an improved switching device for selecting and interconnecting any number of a plurality of plural phase motors.

A still further object of the invention is to provide an improved multiple three-phase switching device which simultaneously selects and then interconnects all phases of a plurality of motors.

A still further object of the invention is to provide an improved switching operation for rapidly interconnecting a selected plurality of threephase electrical devices.

A still further object of the invention is to provide an improved selection switch which simultaneously closes a plurality of contacts under thesame tension.

Although the novel features which are believed to be characteristic of this invention will be pointed outwith particularity in the appended claims, the manner of its organization and the mode of its operation will be better understood by referring to the following description read in accommodate several cameras when a respective number of, companies are shooting scenes. The present invention, therefore, provides a switching system for connecting any selected group of conjunction with the accompanying drawings forming a part hereof, in which:

Fig. 1 is a single line diagrammatic view of a switching system embodying the invention.

Fig. 2 is a diagrammatic view of the-switching arrangement between two load motors and a distributor showing the connections in detail.

3 Fig. 3 is a side view partially in cross section of the switch used in the systems of Figs. 1 and 2 in closed position.

Fig. 4 is apartial cross sectional view of the switch shown in Fig. 3 in open position.

Fig. 5 is a plan view of one of the rotary con--.

tactor plates taken along the line 5-'-5 of Fig. 4.

Fig. 6 is a plan view of one of the switch mounting plates taken along the line 5-5 of Fig. 4, and Fig. 7 is an end view of one of the switch cover plates taken along the line 1-! of Fig. 4.

Referring now to' Fig. 1 showing solely a diagrammatic arrangement of the switching-problem, two soundheads 5 and 5, two recorders I2 and 5, and one camera H; are illustrated, each of which has respective switches 8, 9, i3, i7, and i8 and which are shown with three distributors 28, and 2|. Only this number of elements have been shown for the sake of clarity, it being understood that any number of devices may be similarly connected, as will be explained hereinafter. As shown in Fig. 1, soundheads 5 and 6, through their switches 8 and 9, are shown connected to.

distributor along with recorder i2 through switch l3. Recorder i5, together with the camera l6, are connected through respective switches l1 and iii to distributor 28, the third distributor 2| being idle. The motors used in these units and the distributors are all operated on threephase, but for clarity, the interconnections are shown by single connectors, while the contacts of the switches are limited to three, since only three distributors are shown.

Referring in detail to the connections, it will be noted that soundhead 5 is connected through switch 8 over conductor 23 to distributor i while soundhead 8 is connected over switch 9 and conductor 24 to distributor i, and recorder i2 is connected over switch I3 and conductor 25 to distributor ii. If it were desired to connect soundheads 5 and 6 and recorder i2 to distributor 2|,

switches 8, 9, and I3 would be thrown to their center contacts and they would thus be connected over conductors 26, 21, and 28 to distpibutor2l.

Similarly, if the switches 8, 9, and i3 were thrown F distributor over conductors 8i and 38.

Thus, it will be observed that it is possible to connect any one or all of the film advancing units to any one of the distributors. However, such switching units, as illustrated at 8, 9, i3, |'l',a'ndl8, would not function satisfactorily if the switch swingers contacted the center contacts in passing back and forth between the outer contacts. For instance, if distributor 2| was already connected and running in an operating system, and it was desired to switch soundhead 5 from distributor I i to distributor 20, soundhead 5 should not be-connected to distributor 2| in the switching operation. Thus, a simple sliding contact switch is not suitable in actual practice. Thus patch cords have been employed in the past for making these connections.

To show in more detail the manner of connecting the three-plase windings of one machine to the three-phase winding of another machine in the proper-manner, reference is made to Fig. 2

4 wherein the motor for soundhead No. 1 is shown with a three-phase stator winding and a. threephase rotor winding, while distributor No. 1 is shown with three-phase rotor and stator windings, the rotor of which is mechanically driven by a three-phase synchronous motor 40. Also illustrated, are the three-phase rotor and stator windings for the motor of soundhead No. 2, which, of course, could also be the motor of a recorder or a camera. Furthermore, Fig. 2 shows two switches 42 and 44 in diagrammatic form to illustrate the manner of interconnecting the multiple phases of the motors of the two soundheads and the distributor, although it is to be understood that such sliding contact switches are not suitable in actual practice as explained above.

Referring first to switch 42, six curved contact bus bars 46, 41, 48, 49, 50, and 5| are shown with four cooperating contacts for each bus bar, the contacts being arranged equidistant from each bus bar. The switch also has three rotating contact arms 53, 54, and 55 all mechanically interconnected, as shown by the'dotted line, for simultaneous operation. The ends of the arms are insulated from one another to isolate the two circuits. Similarly, the switch 44 has six crescent bus bars 58, 59, 68, 6|, 62, and 63 with respective contacts and three rotatable contact arms 55, 55, and 61. The position of the contact arms of the two switches are such as to interconnect the two soundhead motors and the distributor for operation.

As mentioned above, to operate the units shown in Fig. 2 in synchronism, it is necessary that the stators of the distributor and the stators of the load motors be connected to the three-phase power source, and the rotors of the distributor and load motors be connected together. These connections will now be traced through the switches 42 and 44. From the three-phase power source, power may be impressed on the synchronous motor 40 and simultaneously on the stator of distributor No. 1. Starting from point a on the stator of distributor No. 1, this point is connected over conductor I0 and conductor H to a contact 12 of the second section of switch 42. As contact 72 is connected to bar 48 through the left-hand end of arm 54, the connection continues from bar 48 over conductor 13 to point a on the stator 01 the motor of soundhead No. 1. Now, starting from point 12 on the stator of distributor No. 1, this point is connected to point b of the motor stator of soundhead No. 1 over conductor 15, conductor 16, contact Tl, left-hand end arm 53, bar

46, and conductor 18. Similarly, the point c on the stator winding of distributor No. 1 is connected to point e on the motor stator of soundhead No. 1 over conductor l9, conductor 80, contact 8|, left-hand end of contact arm 55, bar 58, and conductor 82.

Since the motor stator winding of soundhead No. 2 must also be connected to the three-phase power source and to the other stators if the two motors are to run in synchronism, a circuit may be traced from point a on the stator of distributor No. 1 over conductor 18, conductor 83, contact 84, Y

right-hand end of arm 66, bar 5|, and conductor to point a on the motor stator of the soundhead No. 2. Similarly, from point D of the stator of distributor No. 1, the circuit is over conductor 15,- conductor 88, contact 81, right-hand end of arm 55, bar 59, conductor 88, to point D on the motor stator of soundhead No. 2. From point e of distributor No. l, the circuit is over conductor 19, conductor 89, contact 90, right-hand end of arm 61, bar 66, and conductor 6| to point e on the stator. From the above connections, all three phases of all three stators are interconnected and connected to the three-phase power source.

Similarly, the rotors of the motors of the two soundheads and the distributor are interconnected, the point it on distributor No. 1 being connected over conductor 62, contact 66, right-hand end of arm 66, bar 6|, and conductor 64 to the point d on the motor rotor of soundhead No. 1. From this same point d over conductor 66, contact 66, left-hand end of arm 66, bar 66, and conductor 61, a circuit is made to point d on the motor rotor of soundhead No. 2. From the point e on the rotor of the distributor, a circuit may be traced over conductor 66, contact 66, right-hand end of arm 64, bar 46, and conductor I66 to point e on the motor rotor of soundhead-No. 1. The circuit from the point e on the distributor to the point e on the motor rotor of soundhead No. 2, is over conductor I63, contact I64, left-hand end of arm 66, bar 66, and conductor I66. The connecticn for the last phase is traced from point I of the distributor over conductor I66, contact I66, right-hand end of arm 66, bar 41, and conductor I II to point I on the motor rotor of soundhead No. 1, while the last circuit between the distributor and the motor rotor of soundhead No. 2 is over conductor I I2, contact I I3, left-hand end of arm 61, bar 62, and conductor II4 to point I.

A plurality of resistors I I6 are shown interconnected across the rotor windings to provide the proper startin characteristic.

From the above traced circuits, it is realized that with the rotatable contact arms 66, 64, 66,

66, 66, and 61 rotated to the positions shown in the drawings, the motor rotors of the two soundheads and the rotor of the distributor will be interconnected, and the motor stators of the soundheads and the stator of the distributor will be interconnected and connected to the threephase power source. Switch 42 may also connect the motor of soundhead No. 1 to any one of three additional distributors simply by rotating the contact arms 66, 64, and 66. For instance, if these arms are rotated one notch to the next contact, the motor stator windings through bars 46, 46', and 66 would be connected to contacts II6, I I6, and I26, and thus to the motor stator of distributor No. 2. In this new position of the switch, the motor rotor of soundhead No. 1 would be connected over contacts I22, I26, and I24 to the rotor of distributor No. 2, since these contacts are diametrically opposite to respective contacts II6, III, and I26. Similarly,by rotating the arms 66, ,and 66 another notch, the motor stator windings of soundhead No. 1 would be connected to v the stator of distributor No. 3 over contacts I26,

I21, and I26, while the motor rotor of soundhead No. 1 would be connected to the rotor of distributor No. 3 over contacts I6Il, Ill, and I62. Rotation of the arms 63, 64, and 66 another notch may connect the stator or rotor windings to another distributor. The same arrangement is provided for switch 44 for soundhead No. 2 so that the rotation of the arms 66, 66, and 61 will select any distributor for connection to the soundhead No. 2. It is to be understood that additional contacts may be provided for these switches in case a further number of distributors are to be connected. Also, the connections may be made so that all left-hand switch bars may be for the stators and the right-hand bars for the rotors or vice versa.

with the above described triple-armed switches. such as shown at 42 and 44, for each load unit motor any group of motors may be connected to any particular distributor simply by rotating the contact arms to the contact of the selected distributor. However, if intermediate distributor contacts were in use, it would be necessary to by-pass them in some manner to perform the switching operation. Such a switching device is illustrated in Figs. 3 to 'l, inclusive, and will now be described.

The switching device shown in Figs. 3 to '1 operates in twosteps. First, the selection of the proper distributor is made by rotation, and second, the actual connections are made by a longitudinal motion of the switch.' The switch includes a rotatable octagonal or hexagonal shaft or bar I40 at one end of which is mounted a pistol grip handle I by-a pin I42. The trigger of the handle is a bell crank I44 pivoted at I41, having a latch tip I46. and urged into locking position by a spring I46. In Fig. 3. the closed position of the switch is shown wherein the tip I46 is in position behind a flange I46 of a collar I46, while in Fig. 4 the switch is shown in open position with the tip I46 removed from the flange I46.

There-are three switch sections I6I, I62, and I66, each section being identical, so the description of one section is applicable to the other sections. As shown in Fig. 5, each section has a rotatably and longitudinally sliding two element contact plate I66 comprising a disc I66 of insulating material and contact pins I61 and I66, which may be of metal, the pins being diametrically positioned opposite one another on the disc I66. The disc is mounted on a metal sleeve I66, which is pinned by a pin I16 to the shaft I46. The pin I16 is in an elongated slot I12 in the shaft I46 so that the shaft may have a limited movement without moving the plate I66 and the contact pins I61 and I66, as will be explained hereinafter. The disc I66 is urged toward the closed position of the switch by a coil spring I14 positioned between the plate I66 and a collar I16 fixedly mounted on the shaft I46. The remaining portion of each switch section is made up of a dished disc [11 (see Fig. 6) containing two groups of contact switches I16 and I16, each group ineluding five switches, although a different number may be used. These switches are c! the micro contact type wherein a contact member III is brought into contact with a contact member I62 by a spring element I66 adapted to be moved to the right by the contactor pins I61 and I66. The contact elements I62 of the group I16 are all electrically connected to a crescent bus bar I66, while the contacts of group I16 are all electrically connected to a bus bar I61. These bus bars correspond to bars 46 to 6| and 66 to 66 in Fig. 2. A cover plate I66, as shown in Fig. 7, encloses the switches I16 and I16, except for two groups of holes HI and I62, these holes being of a size to permit the passage of the pins I61 and I66 and aligned in front of respective switches I16 and I16.

Thus, to close simultaneously any two diametrically opposite switches in the groups I16 and I16, the shaft I46 is rotated by the handle I" until the pins I61 and I66 are opposite the holes behind which are the switches to be closed, and the handle I is then moved to the right. As the shaft I46 is moved longitudinally to the right, the collar I16 bears against the spring I14, which moves the plate I66 to the right and causes the pins I61 and I66 to enter the two diametrically opposite holes I8I and "I92 selected. The pins thus move the springs I83 and cause respective contactors I 8I' to make contact with contactors I82. All three sections II, I52, and I53 are simultaneously actuated, the springs I14 and slots I12 (see Fig. 3) providing a certain tolerance in the mounting of the switching sections. That is,

if a slight difierence exists between the spacing on the switches which might cause injury and is thus a safety feature. The adjustment is within the limits of the elongated slots I12 in which the, plate fastening pins I18 are located. When the switch is unlocked with the trigger I, the pin I18 insures the removal of the pins from the holes I'9I and I92.

As mentioned above, the group switches I18 and I 19 each have their own bus bar and the pins I51 and I58 will operate one switch in each group. Thus, since one bus bar is connected to one rotor winding and the other bus bar to a stator winding, each group of switches will function in the same manner as the sliding switches in Fig. 2, but will permit a selection of any distributor without actually making connections with the intermediate terminating contacts of any distributor in use at the time. Furthermore, with the pins I51 and I58 in the holes I9I and E92, the switch is locked against rotation so that it is necessary to disconnect any motor served by the switch before it can be connected to another distributor.

The switch sections I5I, I52, and I53 are mounted on four bolts, two of which are shown at 280 and "2M and on which insulating members, two of which are shown at 284 and 205, are placed to maintain the proper separation between the switch sections. The mounting bolts may be used to mount the entire switch on a. panel, such as shown at 281. To provide an accurate and definite positioning of the pins new and its with respect to the holes GM and I92, 9. serrated or toothed wheel or pinion 288 is keyed to the shaft Mil. Contacting the gear 288 is a resiliently mounted pin 7H8 urged toward the gear 208 by spring 2i I which may be held in position by a set screw M2. The pin, spring, and set screw are mounted in the block casting 2% which is attached to the panel by screws 2B5. This positive step arrangement insures that the pins I51 and I58 are properly aligned with selected holes tilt and I82 before the contact pins are moved longitudinally.

' Electrical connections may be made to the bus bars I88 and I81 at terminals m and 2I8pwhile each of the contact elements lei has an individual terminal, such as shown at MS and 228, the latter corresponding to contacts, such as shown at 8|, I89, I28, etc., in Fig. 2. Thus, instead of a terminal rack with sockets, plugs, and. patch cords, a panel is provided on which is mounted a selection switch for each load motor. When any load motor is to be connected to any particular distributor, it is only necessary to rotate the handle I to the indicated distributor and then push it"longitudinally toward the panel to simultaneously make the six connections. During the selecting operation, there is no danger of contacting any live distributor, since signal lights indicating the live distributors are positioned on the switch panels.

The trigger I locks the switch in closed position (see Fig. 3). If four or live load motors are ,to be connected to the same distributor, the respective number of switches will be rotated to that distributor and the connections made in the same manner. It is realized, therefore, that the switching operation and the interconnecting of any specified number of units as a synchronous running system may be very rapidly accomplished. To disconnect a motor, the operator places a finger on the trigger I and pulls, the trigger releasing the latch I48 to permit the shaft to be shifted to the left, which allows the spring contactors I8I to break contact with elements I82.

We claim:

1. In a switching system for a plurality of selfsynchronous motors, a plurality of load motors and a plurality of distributors adapted to control the acceleration and speed of said load motors, comprising switching means corresponding in number to the number of said load motors and adapted to select and connect any one or more of said load motors to any one of said distributors, each of said switching means comprising a rotatable plate having contact pins thereon, a pinrality of fixed normally open contacts, and a, retatable shaft adapted to rotate said plate for making the selection of said fixed contacts and to be moved longitudinally for causing said pins to close the selected contacts to make the eonnection.

2. A switching system in accordance with claim I l, in which each of said switching means comprises a plurality of sections, each section having one of said rotatable plates and plurality of fixed contacts, and each section being simultaneously actuated and adapted to connect one phase of said load motors to one phase of said distributor.

3. In a switching system for connecting a pin-- rality of three-phase load motors to a selected one of a plurality of three-phase distributors,

-' comprising a switch having a 'bus bar for each phase of the stator of a load motor and a bus bar for each phase of the rotor of said load motor, fixed contacting elements adapted when actuated to connect the phases of the rotor and stator of a selected distributor to the rotor and stator phases of said motor, a rotatable plate having actuating pins thereon, a fixed plate having apertures through which said pins are adapted to pass to actuate said contacting elements, rotation of said plate selecting any particular contacting elements to be actuated by said pins, and means for moving said plate longitudinally for causing said pins to actuate selected contacting elements.

4. A switching system in accordance with claim 3, in which said rotatable means is adapted to be locked when said contacting elements are actuated.

5. In a switchin system for a self-synchronous motor system having a plurality of load motors and a plurality of distributors comprising switchl ing means for each of said load motors, said means including a multi-sectional switch, each section having a pair of, bus bars, one has bar of each section going to a phase of said motor rotor and the other bus bar of each section going to a phase of said motor stator, contacting elements adjacent said bus bars and connected to the phases of different distributors, a rotating element for each section for selecting the distributor contacting elements to which said bus bars -windings of said other motors, a rotatable member for selecting any desired terminals of said other motors,means for preventing connection between said terminals during the selection of said terminals, and means for longitudinally actuating said rotatable member to make contact between said motor terminals and said selected terminals after selection thereof is made.

8. A switching system in accordance with claim 7, in which said switching device has a section for each phase of said motors including a rotatable member for each section, said actuating means rotating and actuating all of said members simultaneously.

9. A switching device comprising a plurality of cup members, a plurality of opposing switch contact elements arranged circularly about the center of said cup members, a shaft extending through the centers of all of said members, said shaft being rotatable and longitudinally movable in said members, and a corresponding plurality of elements mounted on said shaft adjacent said cup members and having projections therefrom adapted to bring opposing contact elements into contact when said shaft is moved longitudinally in one direction, said elements being rotatable with said shaft to select the contact elements to be brought into contact.

DANIEL J. BLOOMBERG. WALDON O. WATSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,110,027 Aitken Sept. 8, 1914 1,583,578 Crocker May 4, 1926 1,889,514 Cook Nov. 29, 1932 2,008,404 Schaelchlin July 16, 1935 2,301,910 Lootens Nov, 10, 1942 2,354,329 Miller July 25, 1944 

